Steam boiler with forced-draft furnace



C. KOHLER.

STEAM BOILER WITH FORCED DRAFT FURNACE.

APPLICATION FILED MAR. 17, 1920.

1 4233359 Patented. July 18,1922.

awa e es wr t en.

STEAM BOILER WITH FORGED-DRAFT FURNACE.

i'neass Specification of Letters lPatent.

Patented July 18, 1922.

Application filed March 17, 1920. Serial No. 366,659;

To all w 7mm it may concern Be it known that l, CONRAD KoHLnR, a citizenof the Republic of Switzerland, residing at Hardturmstrasse 19, Zurich,Switzerland, have invented certain new and useful improvements in SteamBoilers with Forced-Draft Furnaces; and I do hereby declare thefollowing to be a clear, full, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same, reterence'being had to the accompanying drawingand to letters or figures of reference marked thereon, which form a partof this specification. l I

This invention relates to improvements in steam boilers with forceddraft furnaces and particularly to draft-furnaces in which the air isadmitted into the ash-pit under the grate for increasing the draft andpromoting combustion. a I

Steam boilers with forced draft-furnaces of the type mentioned abovepresent the disadvantage that the opening of the fire door is alwaysdangerous, as flames or at least noxious gases may be driven out by theforced draft when the fire door is opened.

The object of the present invention is to eliminate the drawbackreferred to. To this end ahlast device is provided which is connected tothe fire box previous to the opening of the fire door, whilst the aircurrent from the blower to the ash-pit is cut off. The blast device maybe worked by the compressed air from the under-grate blower, in whichcase a change-over device is provided that is adapted to efiect aconnection between blower and blast-device and to close the connectionbetween blower and ash-pit. The blastdevice may also be worked by meansof the draft induced by the running speed of the vehicle on which theboiler is mounted. v

The accompanying drawing illustrates by way of example several modes ofcarrying out the invention. All these are a plied to steam-locomotives,in which the danger, that the flame or noxious gases on opening thefurnace door are driven into the cab, exists in a higher degree becausethe air-current induced .by the speed of the locomotive produces adepression in the cab.

In the drawing:

Fig. 1 is a diagrammatic longitudinal section through a locomotivefitted with improvements according to the invention.

above described manner.

Fig. 2 is a modification of a detail of Fig. ,4.

Fig. 8 is a longitudinal section through a locomotive showinga modifiedarrangement.

Fig. 41- is a longitudinal section through the lower part of thefire-box illustrating special means for reducing the pressure in thebox.

Fig. 5 is a view similar to Fig. 4, showing undenpressuro means for-theash pit.

An eight wheel locomotive isshown diagrammatically in Fig. 1. It isdriven by a steam-turbine lplaced on the front of the locomotive, thedetails of the drive are not shown. When working normally the exhauststeam from the steam turbine is led to a surface-condenser (not shown inthe drawing). When the locomotive is stopping or when an increase of thedraft in the boiler furnace is necessary, the exhaust steam is led to ablast-device 2, from where it passes through the stack and, acting as anejector, causes the gases in. the smoke box 4 to escape through thestack. When working normally a blower 5 compresses air and forces itthrough pipe 6 into the ash-pit 7. From there itpasses through the gate8 and the fuel. The gases of combustion flow from the fire-box 9 throughthe boiler tubes 10, into the smoke box 41 and escape through thechimney I In ord .r to prevent the noxious gases from passing throughthe door 11 of the fire box into the cab when the door 11 is opened, itis necessary to stop first of all the blower 5 or to stop at least itseffect on the combustion by closing the conduit 6 by means of a flapvalve 12. Then the flap valve 14 inserted in the conduit 13 which hasbeenclosed up till then, is opened to eliminate quickly anyover-pressure in the fire box 9 and to generate an under-pressure inthis box. Fig. 1 shows the connections between the parts arranged andset in the The compressed air from the blower 5 flows along conduit 13into the blast device 2 arranged inside the smoke box 4, the combustiongases contained in the fire box 9, the boiler tubes 10, and the smokebox 4:, are carried away with the air into the stack 3 and the desiredunder-pressure is thus generated inside the fire-box 9. The door 11 maynow be opened without fear that flames or noxious gases willburst intothe cab. To ensure that flap valve 12 has been closed and flap valve 1 Lopened before the door 11 is opened, a lever 15 may be arranged in frontof the door 11 by means of which lever and connecting rods 16, 17connecting said lever up to the valves 12 and 14:, the latter areactuated. In order to open the door 11, lever 15 has first to be rockedon its fulcrum 18 towards the left which movement brings the valves 12and 14 into the desired positions. The furnace door 11 is locked untilafter this movement has been carried out.

When the furnace door 11 is to be opened during the running of thelocomotive at full speed, under-pressure is produced by a pipe 21 theaxis of the opening ofwhich is arranged vertically as shown in Fig. 4-,or which is bent towards the rear as shown in Fig. 2. The current of airinduced in the pipe 21 by the speed of the vehicle generates anunder-pressure inside said pipe, whereby combustion gases are drawn fromthe fire-box 9, until an under-pressure is generated therein. Theconduit 21 can be closed by means of a flap-valve 28. Instead ofconnecting a conduit 21 to the fireboX 9, a pipe 25 fitted with a flapvalve 9A may be connected to the ash-pit 7, Fig. 5.

The modification of the invention shown in Fig. 3 consists in a conduit29, that can be closed by means of aflap-valve 28, which connects theash-pit 27 with the smoke box. This construction is based on theassumption that the lifting power, to which the heated gases aresubjected by the draft action of the stack 80, suffices to cause aquantity of gas to be drawn out of the ash-pit by conduit E29 and toescape through the stack 30, whereby an under-pressure is generated inthe ash-pit 27 and the fire-box 31, sufficient to allow the fire-boxdoor 32 to be opened without any danger. Obviously the connection fromthe blower 83 to the ash-pit 27 has to be closed by flap-valve 34 ashort time before the furnace door is opened.

I claim:

1. In a steanrboiler with forced draftfurnace, the combination of afurnace consisting of a fire-box with fire door and closed ash-pit, anunder-grate blower, a conduit connecting the blower and ash pit, a blastdevice, means including said conduitconnecting the ash pit with theblast device, and means for opening and closing the conduit and saidconnecting means so that the pres sure above atmospheric inside the firebox is removed and an under-pressure is generated.

2. In a steam-boiler with forced draft furnace, the combination of afurnace consisting of a fire-box with fire-door and closed ash-pit, anunder-grate blower, a conduit connecting blower t0 ash-pit, a blastdevice, a closing device inserted in said conduit, and means to set saidclosingdevice so that the pressure above atmospheric inside the fireboxis removed and an under-pressure is generated by said blower to permitopening the fire-door without danger.

3. In a steam-boiler with forced draftfurnace, the combination of afurnace consisting of a fire-box with firedoor and closed ash-pit, anunder-grate blower, a conduit connecting blower to ash-pit, a blastdevice, a conduit connecting blower to blast device, a closing deviceinserted in each of said conduits, and means to set said closing devicesso that the pressure above atmospheric inside the fire-box is removedand an underpressure is generated which permits opening the fire-doorwithout danger.

a. In a steam-boiler with forced draftfurnace, the combination of afurnace consisting of a fire-box with fire-door and closed aslrpit, anunder grate blower, a conduit connecting blower to ash-pit, a blastdevice, a conduit connecting blower to blast device, a closing deviceinserted in each of said conduits, and means to set said closing devicesso that the connections with the blower are changed over from theash-pit to the blast device whereby an under-pressure is generated intothe fire-box which permits opening the fire-door without danger.

5. In a steam-boiler with forced draftfurnace, the combination of afurnace consisting of a lire-box with fire-door and closed ash-pit, anunder grate blower,- a conduit connecting blower to ash-pit, a blastdevice, a conduit connecting blower to blast device, a closing deviceinserted in each of said conduits, and means to prevent the fire-doorfrom being opened until after said closing devices have been set by saidmeans so that the pressure above atmospheric inside the fire-box isremoved. and an under-pressure is generated.

In testimony that I claim. the foregoing as my invention, I have signedin name.

CONRAD nonnnn.

